Production of silane by the use of a zinc catalyst



Aug. 21, 1962 o. E. RINGWALD 3,050,366

PRODUCTION OF SILANE BY THE USE OF A ZINC CATALYST Filed July 15, 1959 INVENTOR OWEN E. RINGWALD ATTORNEY United States Patent Ofifice 3,050,366 PRODUCTION OF SILANE BY THE USE OF A ZHQC CATALYST Owen E. Ringwald, Wilgton, Del., assiguor to E. I. du

Pont de, Nemours and Company, Wilmington, Del., a

corporation of Delaware Filed July 15, 1959, Ser. No. 827,311 13 Claims. (Cl. 23-204) This invention relates to the substitution of hydrogen 7 atoms for the silicon-bonded halogen atoms in halogen-.

discloses such areplacement by reacting the silane with hydrogen and silicon at temperatures above 400 C. Also, US. Patent 2,406,605, referred, to above, substitutes hydrogen into silane derivatives by contacting the silane derivative with hydrogen and a hydrogen halide. Another method for effecting this hydrogen substitution is disclosed in J.A.C.S., 69, 2692-2696 (-1947), and it reacts the halogen-containing silane with lithium hydride in diethyl ether. However, the use of a less expensive hydride, such as sodium hydride, gives a negligible yield ofsilane under similar conditions. The present invention provides a process which uses the less reactive metal hydrides in substituting hydrogen for halogen in halogen containing silanes.

It is an object of this invention to utilize metal hy- 'dn'des, suchas sodium hydride, in an improved process for substituting one or more hydrogen atoms for siliconbonded halogen atoms in a halogen-substituted silane proved process for producing monosilane by substituting hydrogen for all of the silicon-bonded halogen atoms in.

a tetrahalosilane. A further object is the economical production of monosilane of such high purity as to be suitable for use in the manufacture of semi-conductor quality silicon. 1 a

The objects of this invention are attainedby a process comprising contacting a hydride of an alkalinous metal having an atomic number greaterthan 4 with a halogensubstituted silane compound under anhydrous conditions and in the presence of an ether reaction medium and a zinc catalyst which may be either elemental zinc or a compound of zinc.

The process of this invention can be carried out in standard equipment. It is self-initiating and exothermic. The amount of reac ts used i t leas a stoichiometn' amount of hydride based on the amount of hydrogen" substitution contemplated, and'p'referably therejshouldf The amount of ether used is not particularly critical, but it shouldhe present. at'leastl be an excess of hydride.

* cent of the SlCl4 to be used.

in an amount sufficient-to maintain fluidity in'the reaction mixture. The amount of catalyst used is siibje ctto wide variations, and can range from 1:10 to 'l 5 :l bas ed 1 on the molar ratio of catalyst to. the starting silane con.

pound. A preferred range is from l :8 to 2:'l,'withfa' r tio o from 1 mo Qf cat yst 1d 2 mat of startin s lane being especially preferred. Contact between reactants embodiment, a grinding aid or attritive agent, such as.

rock salt, is added to the reaction mixture to exert an reaction surfaces.

compound. A particular object is to providean imparts are by weight.

attritive action on the metal hydride, thus exposing fresh The attached drawing is a schematic diagram of an apparatus that may be used to carry out the'process ofthis invention.

The following is a detailed description of the drawing: Vessel 1 is a .ml. enclosed jacketed reaction vessel equipped with a 1 /2-inch diameter, disc-type stirrer blade 2. Stirrer shaft 5 is sealed by helium introduced through inlet 6 into bearing 7. The vessel is provided with inlets 3 for introducing helium purge gas and a valved measuring burette 4 for introducing ether and liquid reactants (i.e'., the halogen-substituted silane). Solid materials (i.e., powdered metal hydride, catalysts, and attritive agent, if used) are added to vessel 1 after purging the reaction system with dry inert gas. The system as shown in the drawing will of course have to be opened to introduce the solid materials. Reaction product gases are evolved through the cold condenser 8 which can be cooled by a Dry Ice-acetone mixture. This condenser returns to the reactor as'reflux any ether or unreacted halogen-substituted silane that may be vaporized or entrained during the reaction. The silane product gas is passed through tubing 9. to measuring cold traps l0 and 11 connected by tubing 12. Cold traps 10 and 11 are cooled by liquid nitrogen contained in Dewar flasks 13 and 14, respectively. Any non-condensable gas or silane passing the cold traps is removed through tubing 15, and if monosilane is being produced, it is diluted with nitrogen at T 16 for safety purposes since, under certain conditions, monosilane is highly explosive when mixed with air. This mixture of nitrogen and silane is then discharged through outlet 17 to a hood or other wa t H flO HQWeVeLTthe majo Portion, it n of the silane can be collected as a solid in the cold traps, and it is measured asa liquid by removing the Dewar flask long enough to allow the silane to liquefy. Practically all silane is found in the first trap 10. It the process of this invention is used solelyffor the purpose of experimentation, itmay be desirable to dispose of any monosilane produced by vaporizing it "and burning it in air at outlet 17. If the monosilane does not spontaneously ignite at outlet 17, it should be ignited to avoid formation of an explosive mixture.

In a'specific embodiment using the above-described apparatus, sodium hydride is introduced into reaction vessel 1 as a timely divided, oil-coated powder in an amount stoichiometn'cally equivalent to the amount of silicon tetrachloride to be added from burette 4. Zinc chloride which is used as a catalyst is also placed in reaction vessel 1 man amount equivalent to 50 mol per- In addition, suflicient ether is added .to form a stirrable slurry. The silicon tetrachloride is usually added to the 70 ml. reaction ve's'selin an amount equivalent to 0.05 gm. mol, and his introduced at an'approximately constant rate based on the evolution of silane'product gas; It usually takes about 20 minutes .tointroduce all of the silicon tetrachloride into the reaction vessel. Coldwater is passed through. the jacket ofthe. reactor to eontrol the reaction rate and prevent the reaction from proceeding too rapidly.

. Sodium chloride forms'as-aiby-product in the reaction vessel, and in instances where the formation of this bypro duc tf caiisesi thereaction. mixture to thicken to such an extent as to impair the eifectivehess of the agitator,

.. additional ether oraninert liquid diluent can'be added to maintain effective agitation.

lanai-clearer understanding of the invention, the following specific examples are given. ,These examples are intended to be merely illustrative of the invention, and not in limitation thereof,

I re al example deals with the production of monosilane a ed Au 2 6.

hy reducing silicon tetrachloride with sodium hydride usmg various zinc catalysts, as shown in the table below. The apparatus used was that shown in the drawing After this apparatus was purged with dry helium, the ether reaction media (more specifically described in the table), sodium hydride powder wet with mineral oil, and'zinc catalyst were added to the reaction vessel. In those experiments in which attritive powder was used, it was added along with the metal hydride immediately after it had been heated in an oven or mufile furnace to completely remove moisture. The sodium hydride and catalyst-were Weighed in a dry box. Zinc chloride, when used, was reagent-grade material which was fused to remove water and then pulverized in a dry 'box.. Other catalystsused in this example were also treated to remove moisture-.- The ,water jacket surrounding the re} action vessel was controlled at the temperature indicated in the table by using tap water. Except where otherwise specified "in the examples (see Ex. IV), the cold condenser was cooled to approximately 80 C. by the use of a Dry Ice-acetone mixture. In all the experi inents', shown in the table of this example, the following amounts of reactants were used:

9.3 grams NaH wet with mineral oil (this is equal to 4.6 gms. of dry NaH or 0.2 gin. mol) 5.7 ml. SiCl (equal to 0.05 gin. mol) silane to liquefy and to obtain a reading as to the volume of product obtained.

I Some produotdost through trap due to excessive reaction rate.

in Four more milliliters 4 600 r.p.m.

Example I RunNo...-.---- 1 2 3 4 6 6 Cat t-. No catalyst--- No catalyst.-- Clz. Molar rat o catalys 01 Reaction slurryliquid THF 1 THF Kerosene/THE.

Volume of hquirl 20 ml 18 ml 20 ml./20 ml. Attritivo material None NaCl NaCl,

Weight-.' g 50 g 50 g. Q l 5 -100+200-..-- Powder Powder. Agitation: V I

Speed Slow. Hirh Slow High High High. Temperature (jaeket)--..- 12 C 20 12 C 12 C 17 C-.--...- 12 C Yield, mnnn ilane 0% 11% 42 797 95 89%. Reaction period 6 hrs. 6 hrs. 2% hrs.. 2 hrs hr hrs.

Run No.------- 1 V s 9 10 11 Catalyst--. ZIlClg N 0 catalyst... ZnO ZnC ZnOl Molar ratio, oatalystzSiCls. 3:4. 1:2.. 1:2. Reaction slurry liquid Diethylethen- Dicthyleueglycol- Diethylene-glycol Diethylene-glycol- THF. dimethyl ether. dimethyl ether. dimethyl ether.

, Volume of liquid 50 ml ml ml ml 40 ml. Attritivematerial NaCl. N N rme Na NaOl.

Weig t 25 g-- 25 g. g. Mesh size Powder..----- Powder Powder. Agitation:

Speed H Low 4 Low- Hi h High. Temperature (jacket)--. 12 0 16 0 16 0 12 C 17 0. Yield, monosilane. 72 7 0% 31 76 96%.

Reaction period.. 6 hrs 6 hrs. 6 hrs. 2 hrs. 2 hrs.

Run No 12 13 t 14 15 16 17 Catalyst No catalyst. ZnOl ZnFi ZnBn ZDBI'g ZnC 0;. I Molar ratio, cataly'stzSiCli. 1:2.-. 1:2. 1:2. 1:2. 114. Reaction slurry liquid THF TH THF THF THF THF.

Volume of li uid 20 ml 30 ml 20 ml 20 ml 20 ml 20 ml. Attritive material None N NaCl None NaCl; None.

7 Weight- 25 g. 25 g.

Mesh sire Powder..-'.. Powder- Agitation:

Spee Low High I Hig Low/high.-.--- High Low/high. Time (hours).. 2 hrs/ti hr 2 hrs/2 hrs. Temperature (jacket) 0 35 0.----- 12C 13 0 12 C 12 C. Yield, mono flane 0% 68+% 50-80% 38% 83% 38%. Reaction period 6 hrs. hr 1hr 2% hrs 1 hr 4 hrs.

Run No. 18 19 20 21 22 23 Catalyst ZnO-.-.--- ZnO Zn acetate--- Brass, 50% Cu, 50% Zn. Molar ratio, Catalyst-Sick- 1:2.. 1:2-. 1:2. 23:1.

j Reaction slurry liquid-.. THF THF -THF.---- THF. Volume of limiifl 20 5 ml 20 ml 50 ml. Attritive material--- None NaCl--.- None-.- Brass, Zn-Cu. I Wei ht 25 g. 150 g.

Mesh size Powder. 7 --100. a Agitation: a 1

' Speed Low/high.---- 'High Low.---.-.- Low-.-..--..- High High Time (hours). 3 hrs/3 hr Temperature (jacket)--. 16 12 '1 13 F 13 C 17 0-...-. 19 0. Yield, monosilane---- 27 72 I 32 46 78 Reaction perio 6 hrs. 6 hrs.-. 2% hrs 3 hrs 9s hr 3 hrs.

1 Tetrahydroiuran. 1 Paddle type agitator blade used in thisrun. Y

5 Estimated yield: some product lost due to plugging of condenser.

1 Material functions as attritive material as well as catalyst. V

Example II Note.This example illustrates the use ofcalcium hydride as the reducing agent. The procedure and apparatus used here was the same as that of Example 1, except that 0.1 mol of OaH (dry powder) was substituted for the 0.2 ml of NaH used in Example I.

Note.-Thls example illustrates the use of magnesium hydride as the reducing agent. that of Example I, except that 0.1 molof MgH (dry powder) was substituted for the 0.2 mol of NaH used in Example I. I

The procedure and apparatus used here was the same as 2 over a -minute period, into a reaction mixture containing 0 9.3 gm. NaH Wet with mineral oil (4.6 gins. of dry NaH) 25 gm. rock salt powder ('100 mesh) 3.-4 gmjZnCl Run No 28 29 ml. tetrahydrofuran During the introduction of the SiCl the mixture was g fgg yfighg ffifi' }=|f; catalyst" being stirredat high speed with the disc type agitator, Reaction slurryliquid THE; THI". and the reactlon vessel was cooled with waterin the t tg gi glligjf 32., 6 1 jacket at 6 C. About 90 minutes after theSiCL, was Wei ht 25 grams. added, the viscosity of the reaction slurry mixture was legit a ii gi iz Powder 30 checked by Brookfield (rotating spindle) viscosimeter, Speed Lew igh. giving a reading of approximately 100,000 cps. (centif}f E poise-seconds) at 6 r.p.m., and a reading of approxiac period 3hrs fihrs. mately 10,000 c.p.s. at 60 r.p.m. was obtained. The lower value at the higher rotation speed indicates that Example IV Note-This example illustrates the reduction of various halogen-substituted sllanes. ,The apparatus and procedure used as that of Example I. The sodium hydride used was wet with mineral oil andit weighed 9.3 gms.

On a dry basis, this is equivalentto 4.6 mgs. of NaH, or 0.2 gm. mol.

Run N o 30 '31 32 p 33 34 35 1 Halo-silane. Si(.CH3)("l= Si(CHs)(l= .SizCit. SlBlg.

Moles used- 0.067. 0.067. 0.033. Catalyst. ZnClz. 'ZnClz; ZnCli ZIlClz, Molar ratio Zn halo-silane 3: 3:8 3: 1:2. Reaction slurry liquid. THIS THF THF THF, Volume of liquid 20 ml 7 20 ml 20 ml 35 ml. Attritive material None NaCl- None NaCl.

Weight I 25 g. 25 g. Meshsire Powder Powder, A itation:

g Speed lflzlhighum- High ligwlhlghn High High,

Time (hours) .4 2 Temperature (jacket) '16O 15C- 16C. 22C- 12C. Cold condenser temp -,50C -O 0C. 0 0.- Reaction period -6%hrs. 1% hrs, 5 hrs. 1% hrs 3 hr Yie1d 63 3%7 41% 97 Product (CH3)SiHs (CH3) 811 s...- 'Su e, 81 4, and hig er Sir s, S1114, and higher S1H y sllanes sllanes 1 N aH-dryppt. on surface or NaOl powder (0.2 gm. mol).

taneous removal of horonis illustrated in Example V below. p

a ExampleiV g I Using the apparatus and general procedure of Example L, 5.4 m1. of SiCl adulte'rated with L69 ml. of' BF etherate complex (48% BF by weight) was introduced;

the slurry is highly thixotropicl The check readingon glycerol at room temperature was 1000'c.p.s.

After 1 /2 hours a monosilane yield of was. obtained. The product silaue was 'burned inoxygen, and the combustion products were absorbed in water and analyzed for boron' by spectrographic methods.x. No boron ,was detected by'methods capable of detecting 1'0 7 ppmuof boron based on Si.

Thealkalinous metal hydrides that canbe used in this invention include the salt-like hydrides of lboththe alkali metal and the alkaline earth metals; Alkali; metal hydrides that-maybe used-include sodium hydride-"(a preferred material), potassium hydride,1.-rubidium hydride, andcesium hydride. Among the alkalinev earth metals that are contemplated for use in this invention are calcium hydride, strontium hydride; barium hydride, and magnesium hydride; Mixtures of any of the "alkalinous metal 7 hydrides are also useful. All of these metal hydrides react in the solid state, and for this reason it is preferred to use such materials in finely divided form. The metal hydride reactant may be incorporated with the reaction medium as a dry powder or as finely dispersed particles distributed on the surface of inert salts (as, for example, sodium chloride). Also, as will be seen from the foregoing working examples, the sodium hydride may be in the form of a 7 powder wetted with oil to protect it from atmospheric.

deterioration. This latter form, while granular in ap-' pear-ance, is dispersible to its original finely divided particle size of about microns (dia.).

slurry is.so thin that effective grinding of the sodium hy- The halogen-substituted silane compounds useful in the process of the invention include the tetrahalosilanes, as for example SiF SiCl SiBr SiCl Br, and SiI the trihalosilanes, as for example, SiHCl SiI-lBr and Silil the dihalogen-substituted and monohalogen-substituted silanes, as for example SiH Cl and SiI-I Cl; the alkyl halosilanes, as for example aryl halosilanes, .as for example (C H )Cl Si, and (C H BrSi; the halopolysilanes, as for example, Si Cl Si I Si Br and Si Cl thealkyl halopolysilanes, as for example Si Cl.,(CH The halogen-substituted silanes are preferably introduced to the reaction vessel as liquid. However, if desired, these reactants may be introduced in an ether solution, or in the gaseous state.

There is a wide variety of zinc catalysts available for use in this invention. These include the zinc halides such as zinc bromide, zinc iodide, zinc fluoride, particularly zinc chloride. Other zinc materials that are suitable as catalysts are zinc metal, zinc alloys, zinc carboxylates, zinc carbonate, zinc oxide, zinc alkyls, such as (CH Zn, (C H Zn and zinc hydride. The zinc catalyst is preferably used in finely divided form, and, as can be seen from the previous description of this invention, it is usudride is not being obtained, thickening can be accomplished by the addition of more of the grinding agent.

"The choice of grinding agent is not particularly critical providing one chooses a non-contaminating, insoluble material that will exert an'attritive action on the metal hyally added to the reaction vessel along with the ether and solid reactants.

Ethers suitable for use in the process of this invention 7 i dride. Examples of these attritive materials are such inerts as quartz or ilmenite sand; ground fire brick, salts such as the insoluble reaction product salts, as for example NaCl, NaBr, CaCl metal particles, such as steel, aluminum, titanium, zinc, or the like. As will be 'seen from run No. 23 in Example I, anattritive agent con taining zinc can also serve the function of the catalyst. While not critical, in general a particle size in the range of 20 to +200 mesh is preferred for the attritive material. The amount of such material used to obtain effective attritive action will of course vary over a wide range depending upon the reactants, the type of agitation used, and the particular attritive material that is chosen. For example, when SiO or NaCl is used as the attritive material, the weight ratio compared to the metal hydride can vary over a range of from 1:1 to 25:1, or more, depending on the other materials in the reaction slurry. The speed of agitation when using an attritive agent can be varied from a few hundred rpm. to several thousand. However, high speed agitation is particularly effective in improving yield, when attritive agent is used.

The reaction should be carried out under non-contaminating conditions, which means that oxygen and moisture should he excluded from the reaction system. As previously pointed out, the presence of oxygen is dangerous since the end product silane and oxygen can form an explosive mixture. Non-contaminating conditions can be attained by using dry reactants and purging the system with an uncontaminating gas such as nitrogen, argon, or

- helium; 'Such conditions can also be attained by carrying tetrahydrofuran is preferred; If desired, the ethers may" be diluted with an inert organic liquid such as kerosene, heptane, or the like. Such diluents are convenienttq use when by-product alkalinous metal halide has thickened the result in cavitation, thus making it difiicult to obtain the desired solid-liquid contact. Although the reaction will 'proceed at temperatures below 0 C., the latter temperature appears to be the lowest practical limit-if substantial yields are to be obtained in the shortest possible time. When higher boiling ethers are used, one may take advantage of the improved catalytic'efiect obtainable at high temperaturesand temperatures may range up to 200 C.

- orj'higher, depending on the materials used- However, re-

action temperatures of from 5 C. to35 C. are very effective, and theseare preferred for convenience and simplicity. of operation. 1 T f As previously disclosed, a preferred embodiment of this invention contemplates forming the reaction mass into a viscous slurry'bytheaddition of a grinding agent such as out the reaction in acompletely closed system which has been purged with a non-contaminating gas and then evacuatedto remove any residual oxygen or moisture.

The process of the invention has many advantages Among these are the minimum amount of ether required and the low cost of the reducing agent and catalyst materials, which enablespr'oductioiiof the products at a very marked reduction in cost as compared with other process-. es for high-purity silane production; In, particular, monosilane produced from silicon tetrachloride is low in cost and of the highest purity, being especially free from boron.

Since it is obvious that many changes and modifications can be made in the above-described details without departing from the nature. and spirit of the invention, it is to be understood that the invention is not to be limited to said details except as set forth-in the appended claims. g

I claim: a i

1. A process for substituting hydrogen for siliconbonded halogen atoms in a halogen-substituted silane comprising contacting an alkalinous metal hydride selected from the group consisting of sodium hydride and calcium hydride with said silane under non-contaminating conditions and in the presence of an ether reaction mediumselected from the group consisting of tetrahydrofuran, ethyleneglycoldimethyl ether, diethyleneglycoldimethyl ether, triethyleneglycoldimethyl ether, tetraethylenegly- V coldimethyl ether, diethyl ether, 1,4-dioxane, dipropyl ether, diisopropyl ether, and .dichlorodiethyl ether, and

rock salt, and'this viscous slurry is agitated'duringthe 7 5 in the presence of a zinc catalyst selected from the group 9 consisting of zinc halides, zinc metal, zinc alloys, zinc carboxylates, Zinc carbonate, zinc oxide, zinc alkyls and zinc hydride.

2. A process for the production of monosilane comprising contacting an alkalinous metal hydride selected from the group consisting of sodium hydride and calcium hydride with a silicon tetrahalide under non-contaminating conditions and in the presence of an ether reaction medium selected from the group consisting of tetrahydrofuran, ethyleneglycoldimethyl ether, diethyleneglycoldimethyl ether, triethyleneglycoldimethyl ether, tetraethyleneglycoldimethyl ether, diethyl ether, 1,4-dioxane, dipropyl ether, diisopropyl ether, and dichlorodiethyl ether, and in the presence of a zinc catalyst selected from the group consisting of zinc halides, zinc metal, zinc alloys, zinc carboxylates, zinc carbonate, zinc oxide, zinc alkyls, and zinc hydride.

3. The process of claim 2 wherein the alkalinous metal hydride is sodium hydride and the silicon tetrahalide is silicon tetrachloride.

4. A process for the production of monosilane comprising agitating under non-contaminating conditions a reaction slurry consisting essentially of an ether reaction medium selected from the group consisting of tetrahydrofuran, ethyleneglycoldimethyl ether, diethyleneglycoldimethyl ether, triethyleneglycoldimethyl ether, tetraethyleneglycoldimethyl ether, diethyl ether, 1,4-dioxane, dipropyl ether, diisopropyl ether, and dichlorodiethyl ether, a zinc catalyst selected from the group consisting of zinc halides, zinc metal, zinc alloys, vzinc carboxylates, zinc carbonate, zinc oxide, zinc alkyl, and zinc hydride, an attritive agent, a silicon tetrahalide, and an alkalinous metal hydride selected from the group consisting of sodium hydride and calcium hydride in at least a stoichiometric amount based on the conversion of the silicon halide to silane.

5. The process of claim 4 wherein the alkalinous metal hydride is sodium hydride and the silicon tetrahalide is silicon tetrachloride.

6. A process for substituting hydrogen for siliconbonded halogen atoms in a halogen-substituted silane comprising contacting a hydride of an alkalinous metal having an atomic number greater than 4 with said silane under non-contaminating conditions and in the presence of an ether reaction medium and a zinc catalyst.

7. A process for substituting hydrogen for siliconbonded halogen atoms in a halogen-substituted silane comprising agitating under non-contaminating conditions a reaction slurry consisting essentially of an ether reaction medium, a zinc catalyst, an attractive agent, a halogensubstituted silane, and a hydride of an alkalinous metal having an atomic number greater than 4.

8. A process for the production of monosilane com prising contacting under non-contaminating conditions it) silicon tetrachloride and at least a stoichiometric amount of sodium hydride based on the conversion of CiCl to SiI-I, and in the presence of tetrahydrofuran as a liquid reaction medium and zinc chloride as a catalyst.

9. A process for the production of monosilane com- Q prising contacting under non-contaminating conditions silian attritive agent, silicon tetrachloride, and sodium hydride in at least a stoichiometric amount based on the conversion of the silicon tetrachloride to silane.

11. A process for the production of monosilane comprising agitating under non-contaminating conditions a reaction slurry consisting essentially of tetrahydrofuran as a liquid reaction medium and an inert liquid diluent for said tetrahydrofuran, zinc chloride as a catalyst, an attritive agent, silicon tetrachloride, and sodium hydride in at least a stoichiometric amount based on the conversion of the silicon tetrachloride to silane.

1 2. A process for the production of monosilane comprising contacting under non-contaminating conditions silicon tetrachloride and at least a stoichiometric amount of calcium hydride based on the conversion of SiCL, to SiH and in the presence of tetrahydrofuran as a liquid reaction medium and zinc chloride as a catalyst.

13. A process for the production of monosilane comprising agitating under non-contaminating conditions a reaction slurry consisting essentially of tetrahydrofuran as a liquid reaction medium, zinc chloride as a catalyst, an attritive agent, silicon tetrachloride, and magnesium hydride in at least a stoichiometric amount based on the conversion of the silicon tetrachloride to silane.

References Cited .in the file of this patent FOREIGN PATENTS France Ian. 5, 1959 France Jan. 19, 1959 OTHER REFERENCES UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 8 O5O 366 August 21 1962 Owen Ringwald It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Pat corrected below.

Column 9 line 49,, for column 10,,

attractive" line 2 "C101 read SiCl read attritive :SEAL) kttest:

ERNEST w. SWIDER DAVID L. LA-DD Lttesting Officer I Commissioner of Patents 

1. A PROCESS FOR SUBSTITUTING HYDROGEN FOR SILICONBONDED HALOGEN ATOMS IN A HALOGEN-SUBSTITUTED SILANE COMPRISING CONTACTING AN ALKALINOUS METAL HYDRIDE SELECTED FROM THE GROUP CONSISTING OF SODIUM HYDRIDE AND CALCIUM HYDRIDE WITH SAID SILANE UNDER NON-CONTAMINATING CONDITIONS AND IN THE PRESENCE OF AN ETHER REACTION MEDIUM SELECTED FROM THE GROUP CONSISTING OF TETRAHYDROFURAN, ETHYLENEGLYCOLDIMETHYL ETHERE, DIETHYLENEGLYCOLDIMETHYL ETHER, TRIETHYLENEGLYCOLDIMETHYL ETHER, TETERAETHYLENEGLYCOLDIMETHYL ETHER, DIETHYL ETHER, 1,4-DIOXANE, DIPOPYL EHER, DIISOPROPYL ETHER, AND DICHLORODIETHYL EHTER, AND IN THE PRESENCE OF A ZINC CATALYST SELECTED FROM THE GROUP CONSISTING OF ZINC HALIDES, ZINC METAL, ZINC ALLOYS, ZINC CARBOXYLATES, ZINC CARBONATE, ZINC OXIDE, ZINC ALKYLS, AND ZINC HYDRIDE. 